Apple has announced the Apple Watch Series 4. It’s the first real redesign of the wearable since Apple introduced it in 2014, but the changes aren’t so drastic that you won’t recognize it as an Apple Watch. The Series 4 comes with an upgraded display, and you can choose either a 40mm or 44mm model. Even though the screens on the new models are bigger, the overall body of the Watch is roughly the same as previous models, so you shouldn’t notice much of a difference on your wrist.
Smart watch Company OS Android version iOS version CPU Type Bluetooth NFC Developer Options GPS Notify Link Loss Alert Notify Missed Call Notify Timer Notify View Content Call Conversation Find My Phone Voice Control Respond to Notifications Notify Sound Notify Backlit Screen Notify Vibration Ambient Light Sensor Gyroscope Magnetometer Multi-touch Accelerometer Dust and Water Resistance Clock Display Type Screen Size, Inches Screen Resolution, pixels Pixel density, ppi Display Technology Average Battery Life, days Battery Capacity, mAh Battery Technology Case Diameter, mm Case Thickness, mm Wrist Band Width, mm Weight (main unit+watchband), g Wristband Options Replaceable Wristbands LED Flashlight
Like other Fitbit devices, the Charge 3 takes little effort to set up. It works with Android and iOS devices, and all you need is the Fitbit mobile app to use it. Choose the Charge 3 from the list of devices you can pair via Bluetooth to your smartphone or tablet, and follow the on-screen instructions. After setup, you may want to also edit basic information that the Charge 3 uses when tracking activity, such as your age, height, weight, and the activity metric you care most about (steps, active minutes, etc).

If fitness is your top priority, the Apple Watch Series 1 has a good number of shortcomings compared with a dedicated fitness tracker. It doesn’t have onboard GPS, so you’ll need to carry your iPhone to accurately track outdoor activities, like running or cycling, and it’s not waterproof enough for swimming. And unlike a dedicated fitness tracker, the Apple Watch can’t automatically detect and track workouts—you have to manually start it—though this feature is coming with new Watch software this fall. And Apple’s built-in Activity app doesn’t provide much detail, so if you want to dig into your fitness data, or access sleep tracking at all, you have to download third-party apps.

The operating system you choose depends solely on the type of smartphone you have because the smart watch is paired with your smartphone. If you own an Android smartphone, your smart watch should have Android Wear or Tizen. If you own an iPhone, choose an Apple Watch. For example, the Samsung Gear S3 runs Tizen and is compatible with both the Android and iPhone.
The Series 4 now has several new health-focused features, which are very intriguing, including the ability to detect when you fall and even alert emergency contacts if need be, as well as an electrical heart rate sensor that works with an app to alert you to heart health issues. The electrocardiogram (ECG) app has been certified by the Food & Drug Administration, but it's not out yet.
We test every new smartwatch to gauge its design and comfort. If it’s not stylish and comfortable enough to get you from an early morning workout to the office to a night out, you probably won’t wear it every day. Most smartwatches are also fitness trackers, so we put all of its sensors to the test, from step counts to heart rate to GPS (when applicable).